Roughly half of cardiac arrest patients experience telltale warning signs that their heart is in danger of stopping in the month preceding their attack, new study findings suggest.

Those symptoms can include any combination of chest pain and pressure, shortness of breath, heart palpitations, and flu-like sensations (such as nausea, back pain and/or abdominal pain), the researchers said.

The problem: less than one in five of those who experience symptoms actually reach out for potentially lifesaving emergency medical assistance, the investigators found.

"Most people who have a sudden cardiac arrest will not make it out alive," warned study co-author Dr. Sumeet Chugh, associate director of the Heart Institute and director of the Heart Rhythm Center at Cedars-Sinai Medical Center in Los Angeles. "This is the ultimate heart disease, where you die within 10 minutes. And less than 10 percent actually survive," he said.

"For years we have thought that this is a very sudden process," Chugh added. "But with this study we unexpectedly found that at least half of the patients had a least some warning signs in the weeks before. And this is important, because those who react by calling their loved ones or calling 911 have a fivefold higher chance of living. So, this may open up a whole new paradigm as to how we may be able to nip this problem in the bud before a cardiac arrest even happens."

Chugh and his colleagues published their findings in the Jan. 5 issue of the Annals of Internal Medicine.

Though many people use the terms interchangeably, cardiac arrest is not the same as a heart attack. While a heart attack results from arterial blockage that cuts off blood flow to the heart, a cardiac arrest occurs when the heart's electrical activity goes awry and the heart stops working.

Upwards of half of all heart-related deaths in the United States occur as the result of cardiac arrest, killing 350,000 Americans every year, the study authors noted.

The new study focused on nearly 840 patients, aged 35 to 65, whose symptoms were tracked prior to experiencing a cardiac arrest between 2002 and 2012. Three-quarters were men, and all were enrolled in an ongoing study in Oregon.

The result: 50 percent of men and 53 percent of women experienced at least some warning symptoms before their hearts stopped.

Chest pain, said Chugh, was the most common symptom among men, while shortness of breath was the most common among women.

More than nine in 10 of those who had symptoms said they resurfaced 24 hours before their cardiac arrest, according to the study.

But only 19 percent called 911. Those who did were more likely to have a history of heart disease or chest pain that wouldn't subside.

The upside: nearly one-third of those who called 911 survived, versus 6 percent among those who did not, the researchers reported.

"It's not that everyone with chest pain is going to get a cardiac arrest," stressed Chugh. "It could just be too much exercise or heartburn."

But for people with a history of heart disease, it is more likely that these symptoms signal a real problem, he added.

"Still, this is our first foray into symptom identification," Chugh said. "We cannot yet say what patients should do until we look into this further."

Nevertheless, Dr. John Day, president of the Heart Rhythm Society and director of Heart Rhythm Services at Intermountain Medical Center Heart Institute in Murray, Utah, described the study findings as a "wake-up call for patients and doctors."

Day said that "the problem, of course, is that many of these symptoms may have other explanations. Flu-like symptoms, which can affect nearly everybody at some point during the winter, is a vague thing to really put your finger on and know that it's about your heart. So it's certainly challenging to find the right signal through all the noise," he added.

"But these signs should not be ignored," Day said. "Particularly if you have risk factors for heart disease, such as a family history of heart problems or high blood pressure, cholesterol, diabetes or a known heart condition."